The Studio Projects VTB1 is an outstanding, full-featured tube mic preamp at a knockout price!
The Studio Projects VTB-1 is the ultimate in low cost mic preamplifier technology. Incorporating true class A/B switching, the VTB-1 is a totally discrete circuit. Unique to the VTB-1 is the "Tube Drive" - a variable drive to a 12AX7, that lets you blend as little, or as much of the Tube Drive as you want. This gives the VTB-1 the most flexibility of any mic preamplifier in it's price class - from a pristine solid state sound, to any combination of Tube Drive you choose... even hard distortion for guitars and bass! The Studio Projects VTB-1 is a real "must-have", and the perfect mic preamplifier for any microphone!

Mic or Line In to Balanaced or Line Out: <0.0015% (Blend set full CCW- no tube)

Mic EIN: -128dBu (150 ohm source, 60dB gain)

Frequency Response (20-20kHz, ref 1kHz):

-20dBu input, +15dBu output Mic In to Bal Out: +0 /-0.25 dB

0dBu input, +15dBu output Line In to Bal Out: +0 /-0.5 dB

Phase Response (20-20kHz, either input): Input Impedance:

Mic Input (Rear switch in 200 ohm position): 2000 ohms

Mic Input (Rear switch in 50 ohm position): 300 ohms

Line Input (Front panel TRS jack): 1.5 meg ohms

Output Impedance:

Male-XLR Balanced Output: 100 ohms (50 ohms each leg)

TRS Line Out: 300 ohms (Impedance Balanced)

Insert Jack (TRS):

Nominal Level: Approx 0dBu

Located between SS preamp stage and tube/output stage

Tip=Send: 50 ohms output impedance

Ring=Return: 7500 ohms input impedance

For the Best Tube-Sound Results
The VTB1's tube operates best when provided with a solid signal. The best way to accomplish this is to use the on-board metering to set the internal levels. Press the Meter Select switch IN, the meter will now display the signal level within the preamp, just before the tube stage. Adjust the GAIN control to get a meter reading within the 0 to +8 range. With the OUTPUT control at "0", start turning the BLEND control clockwise until the desired sound is heard. Depending on the source material, more or less BLEND will be needed. If the output level is too high or low for your following equipment, adjust the OUTPUT control to compensate. This won’t change the sound of the blended signal, just the overall level.

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